non-Hodgkin Lymphoma Xenografts Research Articles

Coadministration with bendamustine restores the antitumor activity of obinutuzumab in obinutuzumab-resistant tumors.

The glycoengineered, humanized anti-CD20 antibody obinutuzumab is indicated for previously untreated or relapsed/refractory CD20-positive follicular lymphoma (FL). However, the effectiveness of obinutuzumab retreatment in relapsed/refractory FL after prior obinutuzumab-containing therapy is unclear. To address this issue, we investigated the antitumor activity of obinutuzumab plus bendamustine in obinutuzumab-resistant tumors established from a human non-Hodgkin lymphoma xenograft model. Obinutuzumab-resistant tumors (SU-DHL-4-OR-18-8) were established from an SU-DHL-4 xenograft model by repeated administration of obinutuzumab. Antitumor activity was evaluated based on tumor volume after treatment with obinutuzumab on Day 1, 8, and 15 and/or bendamustine on Day 1 and 2. Intratumoral natural killer (NK) cells/macrophages were evaluated by immunohistochemistry and flow cytometry. In SU-DHL-4-OR-18-8 xenografted tumors, intratumoral NK cells/macrophages after obinutuzumab treatment were significantly decreased compared with parent tumors on Day 4. The endoplasmic reticulum stress sensor phospho-IRE1 was also decreased. In SU-DHL-4-OR-18-8 tumors, bendamustine treatment increased phospho-IRE1 on Day 4 and intratumor NK cells/macrophages on Day 10. Obinutuzumab combined with bendamustine significantly increased antitumor activity compared with each single agent on Day 29, with an increase in chemoattractant CCL6 expression on Day 10. Coadministration of bendamustine in obinutuzumab retreatment may be effective against obinutuzumab-resistant tumors.

High Frequency of CD74 Expression in B-Cell Non-Hodgkin's Lymphoma (NHL) and Targeting with SΤRO-001, a Novel Anti-CD74 Antibody Drug Conjugate (ADC) with Potent I n Vitro Cytotoxicty and In Vivo Anti-Tumor Activity

Introduction: STRO-001 is a novel CD74-targeting ADC comprised of an anti-CD74 human IgG1 antibody (SP7219) genetically incorporating the non-natural amino acid para-azidomethyl-L-phenylalanine (pAMF) with a non-cleavable dibenzocyclooctyne (DBCO)-maytansinoid linker-warhead. Highly efficient and precise site-specific conjugation enabled by cell-free antibody synthesis technology produced a well-defined homogeneous ADC with a drug-antibody ratio (DAR) of 2. Conjugation sites were selected based on highest stability both in vitro and in vivo . The aim of this study was to investigate the expression of CD74 in NHL and explore the therapeutic potential of STRO-001 in B-cell NHL cell lines and xenografts.Methods: The binding affinity of SP7219 to recombinant human CD74 ECD (extracellular domain) and cynomolgus monkey (cyno) CD74 ECD was measured by SPR using a Biacore T200. Biotinylated SP7219 was used for immunohistochemistry (IHC) in NHL tumor specimens. Flow cytometry was used for measuring CD74 expression in NHL cell lines. STRO-001 was used to determine the EC50 and percent span of killing in NHL cell lines. The anti-tumor activity of STRO-001 in NHL xenografts in severe combined immune deficient (SCID) mice was examined.Results: Anti-CD74 antibody SP7219 binds to both human and cyno CD74 ECD with high affinity (KD=0.85nM for human, KD=2.4nM for cyno). Tissue samples from the Department of Pathology at Stanford University were used to evaluate CD74 expression by IHC after appropriate permissions were obtained. Medium to high CD74 expression in >70% of cells was observed in 118/118 (100%) diffuse large B-cell lymphoma (DLBCL), 148/151 (98%) follicular lymphoma and 19/21 (90%) mantle cell lymphoma (MCL) samples. In vitro cytotoxicity assays show potent activity of STRO-001 in a diverse panel of B-cell tumor lines with EC50 values ranging from 0.17-13 nM (Table 1). CD74 cell surface expression is required for STRO-001 cytotoxicity but expression level does not correlate highly with in vitro potency (R2 = 0.4154). STRO-001 exhibits dose-dependent tumor growth inhibition in rituximab-resistant germinal center B-cell-like (GCB)-DLBCL SU-DHL-6 xenografts starting at 2.5 mg/kg weekly x 3 doses. STRO-001 + bendamustine/rituximab (BR) further improves tumor suppression in SU-DHL-6 xenografts compared to vehicle (p = 0.002) or BR alone (p = 0.02). In the activated B-cell (ABC)-DLBCL U2932 model, single doses of STRO-001 produce dose-dependent growth inhibition at 1 and 3 mg/kg and complete tumor regression at 10 mg/kg in 7/7 animals with no tumor re-growth up to > 90 days post-treatment (Figure 1). Studies with an MCL model, Jeko-1, demonstrate robust STRO-001 anti-tumor activity compared to vehicle (p < 0.0001) starting at a single 3 mg/kg dose, with a single 10 mg/kg dose resulting in tumor regression for up to 64 days post treatment (Figure 2). STRO-001 treatment 14 days post tumor inoculation was used to evaluate disease progression in the disseminated Mino MCL model. Vehicle-treated animals developed advanced progressive disease, with median survival of 81 days. In contrast, all Mino xenografts treated with STRO-001 at 3 mg/kg or 10 mg/kg were alive and disease-free at the time of sacrifice 135 days post tumor inoculation (Figure 3).Conclusions: CD74 is expressed with high frequency and intensity in DLBCL, follicular lymphoma and MCL, supporting the investigation of novel biologics targeting this antigen. STRO-001 demonstrates potent in vitro cytotoxicity in multiple NHL cell lines and anti-tumor activity in GCB-DLBCL, ABC-DLBCL and mantle cell lymphoma xenograft models, including prolongation of survival in the disseminated Mino MCL model and prevention of tumor regrowth in the U2932 ABC-DLBCL and Jeko-1 MCL subcutaneous models. Clinical studies of this novel ADC for treatment of B-cell malignancies are under development. [Display omitted] DisclosuresYu:Sutro Biopharma: Employment. Abrahams:Sutro Biopharma: Employment. Embry:Sutro Biopharma: Employment. Li:Sutro Biopharma: Employment. Zhao:Stanford University School of Medicine: Employment. Henningsen:Sutro Biopharma: Employment. DeAlmeida:Sutro Biopharma: Employment. Matheny:Sutro Biopharma: Employment. Kline:Sutro Biopharma: Employment. Yam:Sutro Biopharma: Employment. Stafford:Sutro Biopharma: Employment. Natkunam:Stanford University School of Medicine: Employment. Hallam:Sutro Biopharma: Employment. Lupher:Sutro Biopharma: Employment. Molina:Sutro Biopharma: Employment.

Trph-222, a Novel Anti-CD22 Antibody Drug Conjugate (ADC), Has Signficant Anti-Tumor Activity in NHL Xenografts and Is Well Tolerated in Non-Human Primates

CD22 is a B-cell specific transmembrane glycoprotein belonging to the SIGLEC family of lectins. Its expression is restricted to B lineage cells from the early immature/pre-B-cell stage through the mature naïve stage, and is downregulated on the surface of plasma cells. CD22 is highly expressed on a wide range of malignancies arising from mature B-cells, including NHL (non-Hodgkin's lymphoma), DLBCL (diffuse large B cell lymphoma), MCL (mantle cell lymphoma), MZL, B-cell acute lymphoblastic leukemia, chronic lymphocytic leukemia and small lymphocytic leukemia. The restricted lineage of CD22 and rapid internalization upon antibody binding make CD22 an appealing target for an antibody-drug conjugate (ADC) therapeutic for B cell malignancies. Prior attempts at targeting CD22 using ADC technology have been limited clinically in NHL due to an unacceptable or poor therapeutic index. Subsequently the ADC field has focused on more stable and site specific conjugation of payloads to increase the therapeutic index of ADCs.TRPH-222 is an ADC comprised of an anti-CD22 antibody site-specifically modified at one site in each heavy chain to express formylglycine (FG), allowing for site-specific conjugation of a maytansinoid payload, a protease-insensitive spacer, and a functional group for coupling to an aldehyde on the antibody FG residues. This SMARTAG™ site specific non-cleavable conjugation enforces a maximum drug to antibody ratio (DAR) of 2.0.The aim of this study was to characterize the anti-tumor activity of TRPH-222 in mouse xenografts and tolerability in non-human primates (NHP).In the WSU-DLCL2 xenograft model, once weekly intravenous (IV) dosing of 1, 3 or 10mg/kg or TRPH-222 reduced tumor volume by 51%, 100% and 100% after 28 days. A once every three-week dose of 10mg/kg reduced tumor volume by 100% from pre-dosing measurements. In contrast, rituximab (30mg/kg, weekly) resulted in 55% tumor growth inhibition. In both SU-DHL-2 (DLBCL) and Granta-519 (MCL) xenograft models, weekly dosing at 10mg/kg resulted in tumor stasis.The tolerability and PK of TRPH-222 were evaluated in cynomolgus monkeys. Animals were dosed IV once every 3 weeks (the anticipated clinical dosing schedule) for either 2 (5, 12.5, or 25 mg/kg) or 3 (50 mg/kg) doses. TRPH-222 was well tolerated at all doses evaluated and all animals survived to study termination, with no TRPH-222-related effects on clinical observations or body weight. Aspartate aminotransferase (AST) activity was mildly increased in animals at ≥12.5 mg/kg/dose, while minimal increases in alanine aminotransferase (ALT) activity were noted at 50 mg/kg/dose. Minor microscopic findings of Kupffer cell hypertrophy/hyperplasia were noted in the livers of monkeys treated at 50 mg/kg IV; this finding was not considered adverse based on minimal severity and lack of degeneration/necrosis. Preliminary PK data demonstrate the stability of TRPH-222, as the ratio of the area under the curve (AUC) from day 0-42 for the ADC was ~76-88% that of the antibody backbone suggesting that the ADC has a long half-life and that the linker is stable in vivo.In conclusion, the studies reported here demonstrate that TRPH-222 has significant anti-tumor activity in a range of B-cell lymphoma models and that very high doses of TRPH-222 are well tolerated in monkeys. IND-enabling safety studies are ongoing to support clinical evaluation of TRPH-222 in 2018. These data support the argument that TRPH-222 will have a large therapeutic window due to the stability of conjugation of the maytansinoid payload to the anti-CD22 antibody; doses tolerated in the monkey study described above correspond to human equivalent doses significantly higher than for most ADCs approved or currently under clinical evaluation. To our knowledge, this is the highest dose of a maytansine containing ADC that has been tolerated in monkeys and raises the potential for a best in class therapy for NHL in addition to a best in class ADC technology. DisclosuresMaclaren:Triphase Accelerator: Employment. Levin:Triphase Accelerator: Employment. Lowman:Triphase Accelerator: Employment. Trikha:Triphase Accelerator: Employment; Encycle Therapeutics: Membership on an entity's Board of Directors or advisory committees.

CD19-Chimeric Antigen Receptor (CAR) Engineered Natural Killer (NK) Cell Therapy: Novel “Off the Shelf” Immunotherapy in CD20 Resistant B-Cell Non-Hodgkin Lymphoma (NHL) Cell Lines, Primary NHL Cells, and a Human Lymphoma Xenograft Model

Background: NK-92 is a continuously growing cell line consisting of “pure” (100%) activated NK cells. These cells were subsequently bioengineered to express human anti-CD19 CAR recognizing CD19 B cells (ie, CD19-CAR NK). The goal of this study was to establish the mechanistic rationale for NK-based therapy in B cell NHL (bNHL) and to determine the potency of this targeted “off the shelf” therapy in a host of in vitro bNHL cell lines (including anti-CD20 antibody resistant cells), primary NHL patient derived cells, and an in vivo NHL xenograft model.Methods: bNHL cell lines SUDHL10, SUDHL4, SUDHL2 (diffuse large B cell lymphoma, DLBCL), HF1 (follicular) and Raji (Burkitt) were used. Rituximab- (R) and obinutuzumab- (O) resistant bNHL cell lines (SUDHL2, SUDHL4, SUDHL10) were also established. Patient derived cell lines (EL-5 and KSC) were obtained from primary DLBCL patients via the Tufts Tissue Biorepository. CD19-CAR NK cellular therapy was supplied by NantKwest. In vitro NK cell mediated cytotoxicity was determined using G6PD release (aCella-tox assay), apoptosis by Annexin V & flow cytometry; 10,000 target bNHL cells were co-cultured with effector NK cells at clinically relevant effector to target ratios (E:T 1:1-10:1) for 4 hours. Further, the dynamic efficacy of CD19-CAR NK was determined utilzing droplet based microfluidics & live cell imaging. Global transcriptome analysis was used to establish the biological characteristics of R- & O- sensitive and -resistant bNHL cells & for expression of NK regulatory ligands. Key pathways and drivers were determined using established systems biology approaches (Beheshti A. Cancer Informatics 2015; Dashnamoorthy R. Cancer Res. 2016). Additional functional in vitro ELISA based assays (IFNγ & TNFα) were done. Finally, in vivo studies in SCID mice with a SUDHL10 xenograft model was studied with subcutaneous injections of CD19-CAR NK therapy.Results: We identified that untreated bNHL cell lines expressed high levels of NK activation ligands (CD70, CD86, ITGAL, MICB, etc) and expression of inhibitory ligands were minimal. Profiling analyses also showed that anti-CD20 resistant bNHL cell lines had unique biological properties suggestive of defective IFNγ & TNFα signaling components, while expression of NK regulatory ligands remained mostly intact in both sensitive & resistant bNHL cells. In microfluidics based analyses, we observed >90% death in SUDHL10 and SUDHL4 as well as in the corresponding anti-CD20 resistant cell lines. Global transcriptome analysis revealed that activation of IFNγ signaling was the key transcriptional response to CD19-CAR NK activity, confirmed by increased IFNγ secretion. Gene expression profiling showed activation of inflammatory responses via upregulated immunoregulatory interactions, IFNγ signaling and induction of apoptosis as conserved mechanisms in both parental and anti-CD20 resistant bNHL cells treated with CD19-CAR NK therapy (Fig 1A-B). Cytotoxicity studies showed significantly increased cytolytic activity at E:T ratios (1:1-10:1) via LDH release in all bNHL cell lines (Raji, SUDHL4 and SUDHL10) at 4 hours vs L428 (Hodgkin) or Jurkat (T cell lymphoma) cells (Fig 1C). Increased apoptosis 40-70% (E:T ratios 0.25:1-2:1) was also noted in Raji cells with CD19 CAR NK vs 20% cell death with E:T ratios (0.25:1-2:1) in parental NK-92. Furthermore, CD19-CAR NK co-culture E:T ratio (1:1) resulted in >75% death in O-resistant SUDHL4 (SUDHL4-OR) and 66% death in R-resistant HF1 (HF1-RR) cells demonstrating that anti-CD20 resistance did not appear to impact the effectiveness of cell kill with CD19-CAR NK therapy. Finally, results from studies in SCID mice using a SUDHL10 xenograft tumor model showed significant reduction in tumor volume with CD19-CAR NK therapy vs control cells (P <0.001) (Fig 1D).Conclusion: Altogether, we identified that most bNHL cell lines expressed high levels of NK activation ligands and that their biological properties are suggestive of IFNγ and TNFα signaling signaling suggesting a conserved mechanistic response to CD19-CAR NK cell therapy. Furthermore, CD19-CAR NK cell therapy induced prominent single-agent cytolytic activity against a spectrum of bNHL cells, including primary DLBCL cells, cells resistant to standard anti-CD20 antibody, and also a DLBCL in vivo xenograft model with cell death occurring via immunoregulatory pathways with prominent IFNγ signaling & induction of apoptosis. [Display omitted] DisclosuresBoissel:NantKwest, Inc.: Employment. Evens:Pharmacyclics: Consultancy; Merck: Consultancy; Affimed: Consultancy; Amgen: Consultancy; Seattle Genetics: Consultancy; Celgene: Consultancy; AbbVie: Consultancy; • Spectrum Pharmaceuticals: Consultancy; Kite Pharma: Consultancy; Millennium: Consultancy; Novartis: Consultancy.

A Phase 1, Open-Label, Dose-Escalation Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of Multiple Intravenous Doses of IGN002 Administered Weekly to Subjects with Refractory Non-Hodgkin Lymphoma

Background:Non-Hodgkin lymphoma (NHL) is the most common, adult hematologic malignancy. Despite available treatment, relapse rates are high and novel therapies are warranted. IGN002 consists of an anti-CD20 monoclonal antibody (mAb) fused to interferon-alpha (IFNα) via a short peptide linker. The mAb portion of IGN002 is a chimeric IgG1 antibody with the same amino acid sequence as rituximab. The interferon amino acid sequence is human IFNα2b (hIFNα2b). In nonclinical pharmacology studies using CD20-positive human NHL cells, IGN002 demonstrates compelling anti-tumor effects. When compared to rituximab, IGN002 demonstrated enhanced complement-dependent cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC) effector functions against CD20-positive NHL cells. Moreover, compared to rituximab against normal human primary B-cells, IGN002 displayed higher maximal and more potent ADCC activity. Finally, in xenograft studies with immunodeficient mice using 3 different human NHL cell lines comparing IGN002 to rituximab, IGN002 demonstrated superior median and overall survival in all 3 NHL xenograft tumor lines. Study Design and Methods :This open-label, non-randomized, first-in-human, dose finding Phase 1 study comprises a Dose-Escalation Stage and an Expansion Stage (NCT02519270). In the Dose-Escalation Stage, ascending dose cohorts will be treated in 2 periods until the maximum tolerated dose (MTD) or recommended Phase 2 dose (RP2D) is identified. In Period 1, subjects will receive 2 doses of IGN002 administered weekly. Subjects with no anti-drug antibodies to IGN002 at Week 6 in Period 1 will proceed to Period 2 and receive up to 24 additional doses of IGN002 administered weekly in three 8-week cycles, with no treatment-free interval. In the Expansion Stage, subjects will receive up to 24 doses of IGN002 at the MTD or RP2D administered weekly in three 8-week cycles, with no treatment-free interval. Cohorts 1-5 at dose level 0.1, 0.3, 1, 3, and 10 ug/kg, respectively, have been completed without any dose limiting toxicity (DLT) and enrollment for Cohorts 6-8 is impending. Clinical Endpoints:The primary outcome measures are the evaluation of safety and tolerability of multiple doses of IGN002 administered weekly as an IV infusion to subjects with refractory NHL and the determination of MTD or RP2D of IGN002. The secondary outcome measures include characterizing the pharmacokinetic profile of ascending doses of IGN002, the incidence of anti-IGN002 antibody formation, and assessment of anti-tumor activity (e.g., response rate, duration) of IGN002 using the Lugano Classification criteria for NHL. Eligibility Criteria:This study is enrolling patients &amp;gt; 18 years with an ECOG &amp;lt;2 who have a documented history of immunohistochemistry-confirmed CD20-positive B-cell NHL, including diffuse large B-cell, mantle cell, marginal zone, lymphoplasmacytic, follicular, transformed follicular, or primary mediastinal B-cell lymphoma that is refractory to at least 1 documented regimen containing rituximab or a similar anti-CD20 therapy. Patients must also have measurable disease and adequate organ function. The exclusionary criteria encompass treatment with an approved or investigational chemotherapy or anti-CD20 drug within 28 days of Day 1, treatment with an approved or investigational biologic drug that does not target CD20 within 90 days of Day 1, or radiation therapy within 4 weeks of Day 1. Statistical Methods:The sample size was not predicated on formal statistical considerations. Descriptive statistics will be used to summarize continuous variables. Dichotomous endpoints will be summarized using frequencies, proportions, and exact binomial 95% CI. For subjects treated at the MTD or RP2D in Period 2 of the Dose-Escalation Stage and the Expansion Stage, time-to-event variables will be summarized using the Kaplan-Meier method. Target Accrual:In the Dose-Escalation Stage and Expansion Stage, approximately 9-18 (~3-6 subjects per cohort) and 14 subjects, respectively, will be accrued. Enrollment for Cohort 6 is expected to commence in September 2020. Disclosures Mataveli: Spectrum Pharmaceuticals:Current Employment, Current equity holder in publicly-traded company.

Totality of Scientific Evidence in the Development of ABP 798, a Biosimilar to Rituximab

Background: ABP 798 is a proposed biosimilar to rituximab reference product (RP). Regulatory approval of biosimilars is based on a totality of evidence (TOE) approach which includes similarity in analytical characteristics (structural and functional), in mechanism of action (MoA) -clinical pharmacology, pharmacokinetics (PK), pharmacodynamics (PD), and in comparative clinical studies. Evidence from analytical, functional, clinical PK/PD, and efficacy and safety evaluations indicate that ABP 798 is similar to rituximab RP. Similarity of efficacy and safety in patients with non-Hodgkin lymphoma (NHL) was demonstrated in a randomized, double-blind, comparative clinical study in which the primary analysis was based on data from central, independent, and blinded assessments of disease and the sensitivity analysis was based on data using investigator assessments of disease. Here we present in vitro chemo synergy, preclinical in-vivo tumor efficacy data and show how the results of the sensitivity analysis using investigator assessments of the response rate from the NHL clinical study further add to the TOE supporting similarity of ABP 798 with the RP. Methods: In vitro synergy with chemotherapeutic agents was investigated by assessing the effect of docetaxel, gemcitabine, or doxorubicin with ABP 798 and rituximab RP in SU-DHL-6 cell lines and measured using the ATP-based cell viability endpoint (ATPLite). In vivo efficacy was assessed by evaluating the anti-tumor activity of ABP 798 and rituximab RP in NHL xenograft models in NOD/SCID mice using CD20-expressing RL and Raji cell lines. A sensitivity analysis was conducted to assess the robustness of the results of the primary efficacy endpoint of the proportion of patients with the best overall response of complete response, partial response, or unconfirmed complete response (ORR) in the NHL comparative clinical study using the investigator's assessment of disease on the full analysis set. Waterfall plots of the maximum percent reduction in the sum of the products of the greatest diameters (SPD) for index nodal lesions based on both the central, independent, blinded assessment of disease and the investigator's assessment of disease were used. Results: In vitro study results demonstrated synergistic activity of the combination of docetaxel and ABP 798 or the RP (synergy score = 6.35±0.69 [with ABP 798]; 6.79±0.12 [with RP]). In contrast, combinations with gemcitabine (synergy score = 2.68±0.20 [with ABP 798] and 2.54±0.29 [with RP]) or doxorubicin (synergy score = 1.95±0.56 [with ABP 79]) and 3.23±0.53 [with RP]) were additive. In RL cell lines, ABP 798 inhibited tumor growth similarly to rituximab RP, with no statistical difference between dose groups at 3 and 30 mg/kg (p = 0.951 and p = 0.996, respectively). In Raji cells, ABP 798 and rituximab RP significantly and similarly inhibited tumor growth when compared to an IgG1 isotype control (p &amp;lt; 0.001 for 3 and 30 µg/kg doses). ABP 798, at both dose levels, inhibited tumor growth similarly to rituximab RP by 27-41%, with no statistical difference. In the NHL comparative clinical study, risk difference (RD) of ORR with 1-sided 95% lower and upper confidence limits from the adjusted linear model was 7.7% (-3.2%, 18.6%) using central, blinded, independent assessments of the modified full analysis set based on randomized treatment assignment. The sensitivity analysis using investigator assessments of disease of the full analysis set of all randomized subjects based on the randomized treatment assignment received was RD = 0.5% (-7.8%, 8.8%). Waterfall plots of the maximum percent reduction in the SPD for index nodal lesions further demonstrate similarity of efficacy with central or local assessments of disease. Conclusions: In vitro and in vivo preclinical studies demonstrated chemo synergy and in vivo tumor efficacy. The sensitivity analysis of ORR using local assessments in the NHL comparative clinical study was consistent with results from the primary efficacy analysis; the maximum percent reduction in index nodal lesions was similar for central and local assessments of disease. These results further support that ABP 798 is similar to the RP across a range of efficacy evaluations as well as primary and secondary mechanisms of action and add additional supporting data to the TOE. Disclosures Niederwieser: Novartis: Speakers Bureau; Cellectis: Membership on an entity's Board of Directors or advisory committees; Daiichi: Research Funding; Amgen: Speakers Bureau. Hamm:Amgen: Consultancy. Cobb:Amgen: Consultancy. Thway:Amgen: Current Employment, Current equity holder in publicly-traded company. Forsyth:Amgen: Consultancy; Janssen Pharmaceuticals Australia: Honoraria, Membership on an entity's Board of Directors or advisory committees. Tucci:Amgen: Consultancy. Delwail:Amgen: Consultancy. Hajek:Janssen: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Consultancy, Honoraria; PharmaMar: Consultancy, Honoraria; Oncopeptides: Consultancy. Hanes:Amgen: Current Employment, Current equity holder in publicly-traded company.

Abstract 1674: Correlation of the mutational pattern and gene expression data of patient-derived Non-Hodgkin lymphoma xenografts (PDX) with the response to targeted therapies

Abstract Non-Hodgkin lymphomas (NHL) are lymphoid malignant neoplasms that represent a very heterogeneous group and still pose an important clinical challenge. In particular, the frequent development of resistance to the treatment with standard-of-care (SoC) drugs is associated with a high incidence of disease recurrence. Recent progress in molecular high-throughput profiling has helped to identify genetic drivers for many subtypes of B-cell lymphomas as well as T-cell lymphomas. Target validation and drug development depend on corresponding preclinical models representing the different subtypes. Therefore, we established and characterized a panel of patient-derived NHL xenografts. All lymphoma PDX were derived from peripheral blood, lymph node extirpations or core needle biopsies, respectively, and were routinely implanted subcutaneously into immunodeficient mice. For further characterization, established lymphoma PDX models were treated with SoC (e.g., cyclophosphamide, doxorubicine, vincristine, etoposide) and investigational drugs. To gain a deeper insight into the molecular biology of the lymphoma models, RNA sequencing was performed. More than 20 PDX models from different NHL entities have been successfully established and characterized. We observed heterogeneous individual responses to the SoC treatments as well as to target treatments such as rituximab or ibrutinib. Explorative analysis of RNA sequencing data confirmed the representation of the clinical lymphoma subgroups (e.g. DLBCL, Burkitt, AITL) in our panel of lymphoma models. Based on the RNA sequencing data, the individual Human Leukocyte Antigen (HLA) type of each lymphoma PDX was determined with the aim to enable personalized, HLA type-specific studies. Our lymphoma PDX portfolio provides an exceptional platform for the identification and validation of new targets and allows the preclinical screening of new combinations in translational research projects. Citation Format: Bernadette Brzezicha, Theresia Conrad, Michael Becker, Aitomi Bittner, Martin Janz, Clemens A. Schmitt, Ulrich Keilholz, Jens Hoffmann. Correlation of the mutational pattern and gene expression data of patient-derived Non-Hodgkin lymphoma xenografts (PDX) with the response to targeted therapies [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1674.

Rituximab conjugated iron oxide nanoparticles for targeted imaging and enhanced treatment against CD20-positive lymphoma.

Since its launch in 1997, rituximab (RTX) has extensively improved the treatment of CD20-positive follicular and diffuse large B cell non-Hodgkin lymphoma (NHL). The application of RTX is limited usually by the failed therapy because of resistance. Iron oxide nanomaterials have been explored for cancer detection and treatment in recent years. In this study, a multivalent nanoprobe comprising one Fe3O4 nanoparticle and several RTX antibodies was constructed for the targeted imaging and enhanced treatment of NHL. Poly(ethylene glycol) (PEG)-coated Fe3O4 nanoparticles were fabricated via a thermal decomposition method and ligand exchange. RTX was conjugated onto the surface of the Fe3O4-PEG nanoparticles to form Fe3O4-PEG-nAb (n = 2, 5 or 8) multivalent nanoprobes. These multivalent nanoprobes, with a core size of approximately 11 nm and a hydrodynamic diameter of about 22 nm, showed colloidal stability in buffer solution. The r2 relaxation rate of Fe3O4-PEG-nAb was similar to that of Fe3O4-PEG (309 ± 3.08 mM-1 s-1). The specificity of nanoprobes for CD20-positive Raji cells was assessed on a clinical magnetic resonance imaging scanner. The receptor binding site of one multivalent nanoprobe was more than that of one RTX, exhibiting valence-dependent induction of Raji cell apoptosis, and this effect could be enhanced by complement activation from blood serum added. A similar activity was observed in vivo in a NHL xenograft model. The multivalent nanoprobe treatment significantly reduced tumor burden and enhanced survival in comparison to the RTX group. Our studies demonstrate that the appropriate design and preparation of anticancer antibody-nanoparticle conjugates enable the generation of improved anticancer nanomedicines and could thus provide an efficient cancer theranostic strategy.

Administration of Beta-Emitting Anti-CD37 Radioimmunoconjugate Lutetium (177Lu) Lilotomab Satetraxetan as Weekly Multiple Injections Increases Maximum Tolerated Activity in Nude Mice with Non- Hodgkin Lymphoma Xenografts

Lutetium (177Lu) lilotomab satetraxetan (177Lu-lilotomab) is a novel anti-CD37 radioimmunoconjugate (RIC) currently in Phase 2b clinical trial for treatment of non-Hodgkin lymphoma (NHL). The aim of the current study was to investigate tolerability and anti-tumor efficacy of multiple dosing of 177Lu-lilotomab in vivo. Nude mice with subcutaneous (s.c.) NHL (Ramos) xenografts were given 2, 3 or 4 weekly injections of 300 MBq/kg 177Lu-lilotomab or NaCl. Treatment tolerability was assessed by body weight, hematology and histopathological evaluation. A separate experiment in mice without xenografts was performed to collect long term toxicity data. Mice in this study were dosed more conservatively with the intention that all mice should survive until end of experiment and were administered 2 or 4 weekly injections of 200 MBq/kg 177Lu-lilotomab or NaCl. Total accumulated activity of 900 MBq/kg 177Lu-lilotomab given as three weekly injections was tolerated by nude mice with s.c. Ramos xenografts, which is 50 % higher than the maximum tolerated activity (MTA) of a single injection of 530-600 MBq/kg. In the long-term toxicity animals, the highest accumulated activity tested, 800 MBq/kg, was also well tolerated. Radioactivity-dependent transient reduction in white blood cell and platelet counts occurred in all treated groups, with nadir 1-3 weeks after last injection. This toxicity was radioactivity dependent and consistent with histopathological changes in hemolymphopoietic tissues. Significant tumor growth delay measured as time to reach 4 times intial tumor volume was observed in all groups given multiple injections of 300 MBq/kg 177Lu-lilotomab compared to NaCl control group (p&lt;0.001). In conclusion, weekly injections of 177Lu-lilotomab increase the accumulated MTA from 530 to 900 MBq/kg in nude mice, allowing the total injected activity and hence the radiation dose to tumor to be increased without increasing the toxicity to normal tissues.

Combination of 177 Lu-lilotomab with rituximab significantly improves the therapeutic outcome in preclinical models of non-Hodgkin's lymphoma.

To investigate the therapeutic potential of the next-generation anti-CD37 radioimmunoconjugate 177 Lu-lilotomab satetraxetan (177 Lu-lilotomab) in combination with the anti-CD20 antibody rituximab for treatment of mice with non-Hodgkin's lymphoma (NHL) xenografts. Nude mice with subcutaneous (s.c.) Burkitt's lymphoma Daudi xenografts and SCID mice intravenously (i.v.) injected with Mantle cell lymphoma Rec-1 cells were treated with either 177 Lu-lilotomab or rituximab alone or with the combination of both treatments. Tumour volume, body weight, blood counts and clinical status were monitored. CD20 expression was measured using flow cytometry with fluorescence-labelled rituximab. The combination of 177 Lu-lilotomab and rituximab was synergistic for treatment of nude mice with s.c. Daudi xenografts while it was additive for treatment of SCID mice with i.v. injected Rec-1 cells. Binding of rituximab to NHL cells in-vitro was increased by pretreatment with 177 Lu-lilotomab. Treatment of mice with NHL xenografts with 177 Lu-lilotomab synergistically increased tumour suppression of subsequent anti-CD20 immunotherapy and improved survival. If the same effect is confirmed in a recently started clinical study, it could change the way radioimmunotherapy and CD20 immunotherapy would be used in the future.

Abstract 835: TRPH-222, a novel anti-CD22 antibody drug conjugate (ADC), has significant anti-tumor activity in NHL xenografts and reduces B cells in monkeys

Abstract CD22 is a cell surface protein with expression restricted to mature B lineage cells. It is highly expressed on a wide range of B cell malignancies including NHL (non-Hodgkin's lymphoma), DLBCL (diffuse large B cell lymphoma), follicular lymphoma and MCL (mantle cell lymphoma). CD22 is a clinically validated target for an antibody-drug conjugate (ADC) with approval in B cell acute lymphoblastic leukemia (B-ALL). In contrast, in NHL CD22 targeted ADCs have been limited clinically due to a poor therapeutic index. Subsequently the ADC field has focused on stable and site-specific conjugation of payloads for increased therapeutic index. TRPH-222 comprises an anti-CD22 antibody site-specifically modified at one site per heavy chain to express formylglycine (FG), allowing site-specific conjugation of a maytansinoid payload, a protease-insensitive spacer, and a functional group for coupling to an aldehyde on antibody FG residues. This SMARTAG™ site specific non-cleavable conjugation enforces a maximum drug to antibody ratio (DAR) of 2 with high stability enabling an improved therapeutic index. Studies described here characterize the anti-tumor activity of TRPH-222 in human NHL xenograft models and evaluate the pharmacodynamic effects in peripheral B cells. In WSU-DLCL2 xenografts once weekly intravenous (IV) dosing with either 3 or 10 mg/kg TRPH-222 reduced tumor volume by 100% after 28 days, as did a once every three-week 10mg/kg dose. In SU-DHL-2 and SU-DHL-4 xenograft models, TRPH-222 resulted in dose- and schedule-dependent anti-tumor activity with 91% and 100% tumor growth inhibition respectively at 10 mg/kg once weekly dosing. In the Granta-519 xenograft model, weekly 10 mg/kg dosing resulted in 87% tumor growth inhibition and also significantly inhibited tumor growth following escape from R-CHOP. Cross-species assessment of TRPH-222 binding revealed that TRPH-222 bound to immobilized human but not rat CD22. Similarly, TRPH-222 bound strongly to human and monkey peripheral B cells whereas no binding was observed to rat B cells. The pharmacodynamic effects of TRPH-222 on circulating rat and monkey B cell levels were evaluated following either a single (rat) or repeat (monkey) IV doses of TRPH-222 up to either 60 mg/kg or 50mg/kg respectively. In rats, TRPH-222 did not result in a reduction in absolute B cell numbers in any of the treatment groups. In contrast, B cells in cynomolgus monkey were reduced up to 70% from baseline in peripheral blood at all doses evaluated. In conclusion, the studies reported here demonstrate that TRPH-222 has significant anti-tumor activity in all NHL lymphoma models tested and has activity following R-CHOP escape. TRPH-222 demonstrated a CD22-mediated pharmacodynamic effect in monkeys that was consistent with target binding. IND-enabling safety studies are currently ongoing with TRPH-222 to support clinical development in 2018. Citation Format: Ann P. Maclaren, Nancy Levin, Henry Lowman. TRPH-222, a novel anti-CD22 antibody drug conjugate (ADC), has significant anti-tumor activity in NHL xenografts and reduces B cells in monkeys [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 835.

Abstract 301: Targeting the anti-apoptotic BCL-2 family protein provides an effective and precise therapeutic strategy for NHL

Abstract Background: Despite advances in the treatment of non-Hodgkin's lymphoma (NHL), refractory NHL remains a major clinical challenge. The B-cell lymphoma protein-2 (BCL-2) family is frequently overexpressed in NHL, which is associated with poor prognosis by promoting cell growth and resistance to antitumorigenic agents. In this study, by using different BCL-2 family protein inhibitors, we aim to further classify the survival dependency of NHL for anti-apoptotic BCL-2 family members and explore novel approaches to rationally develop combination therapies by completely blocking the activity of the Bcl-2 family proteins. Methods: Cell viability was determined by CCK-8 assay. Apoptotic activity was confirmed by Annexin V-propidium iodide (PI) apoptosis detection, Western blot analysis and mitochondrial membrane potentials detection analysis. In vivo, NHL xenograft models were established to analyze the antitumor effect of the BCL-2 family protein inhibitors. Results: We evaluated the inhibitory effect of of Bcl-2 targeted inhibitors and synergy in combination with other molecular targeted agents in NHL. While those NHL cell lines with only high levels of BCL-2 protein are sensitive to Bcl-2 selective inhibitor, the dual Bcl-2/Bcl-xL inhibitor APG-1252 and its active metabolite APG-1252-M1 potently induced mitochondria-dependent apoptosis in NHL cell lines that possess high expression of both BCL-2 and BCL-XL proteins. After the treatment of APG-1252-M1, apoptosis including caspase-3 activation, PARP cleavage, and mitochondrial membrane potentials change was observed rapidly within four hours. We further demonstrated that APG-1252-M1 showed synergistic effects with Bruton's tyrosine kinase (BTK) inhibitor ibrutinib in those sensitive cell lines by modulating STAT3 signaling pathways. However, cell lines harboring high expression of anti-apoptotic protein MCL-1 were resistant to APG-1252-M1. Furthermore, we observed that APG-1252-M1 exhibited strong synergistic effect with dual PI3K/mTOR inhibitors NVP-BEZ235 in those resistant cell lines with high levels of Mcl-2 protein. Conclusions: Taken together, our data provide an effective and precise therapeutic strategy for NHL through determining NHL addiction to anti-apoptotic BCL-2 family proteins, and then target-guided application of BCL-2 family inhibitors as a monotherapy or in combination with other molecular targeted agents to completely block the Bcl-2 family proteins, thus to restore the apoptotic cell death. Citation Format: Qiu-Yun Luo, Han-Jie Yi, Xiang-Lei Yan, Miaozhen Qiu, Bao-Xia Li, Lin Zhang, Wen-Tao Pan, Lu-Ping Yuan, Zhen-Yi Liu, Douglas D. Fang, Yifan Zhai, Jian Sun, Da-Jun Yang. Targeting the anti-apoptotic BCL-2 family protein provides an effective and precise therapeutic strategy for NHL [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 301.

CD38-bispecific antibody pretargeted radioimmunotherapy for multiple myeloma and other B-cell malignancies

AbstractPretargeted radioimmunotherapy (PRIT) has demonstrated remarkable efficacy targeting tumor antigens, but immunogenicity and endogenous biotin blocking may limit clinical translation. We describe a new PRIT approach for the treatment of multiple myeloma (MM) and other B-cell malignancies, for which we developed an anti-CD38–bispecific fusion protein that eliminates endogenous biotin interference and immunogenic elements. In murine xenograft models of MM and non-Hodgkin lymphoma (NHL), the CD38-bispecific construct demonstrated excellent blood clearance and tumor targeting. Dosimetry calculations showed a tumor-absorbed dose of 43.8 Gy per millicurie injected dose of 90Y, with tumor-to-normal organ dose ratios of 7:1 for liver and 15:1 for lung and kidney. In therapy studies, CD38-bispecific PRIT resulted in 100% complete remissions by day 12 in MM and NHL xenograft models, ultimately curing 80% of mice at optimal doses. In direct comparisons, efficacy of the CD38 bispecific proved equal or superior to streptavidin (SA)-biotin–based CD38-SA PRIT. Each approach cured at least 75% of mice at the highest radiation dose tested (1200 µCi), whereas at 600- and 1000-µCi doses, the bispecific outperformed the SA approach, curing 35% more mice overall (P < .004). The high efficacy of bispecific PRIT, combined with its reduced risk of immunogenicity and endogenous biotin interference, make the CD38 bispecific an attractive candidate for clinical translation. Critically, CD38 PRIT may benefit patients with unresponsive, high-risk disease because refractory disease typically retains radiation sensitivity. We posit that PRIT might not only prolong survival, but possibly cure MM and treatment-refractory NHL patients.

Bespoke Pretargeted Nanoradioimmunotherapy for the Treatment of Non-Hodgkin Lymphoma.

Non-Hodgkin lymphoma (NHL) is one of the most common types of hematologic malignancies. Pretargeted radioimmunotherapy (PRIT), the sequential administration of a bispecific antibody-based primary tumor-targeting component followed by a radionucleotide-labeled treatment effector, has been developed to improve the treatment efficacy and to reduce the side effects of conventional RIT. Despite the preclinical success of PRIT, clinical trials revealed that the immunogenicity of the bispecific antibody as well as the presence of competing endogenous effector molecules often compromised the treatment. One strategy to improve PRIT is to utilize bio-orthogonal ligation reactions to minimize immunogenicity and improve targeting. Herein, we report a translatable pretargeted nanoradioimmunotherapy strategy for the treatment of NHL. This pretargeting system is composed of a dibenzylcyclooctyne (DBCO)-functionalized anti-CD20 antibody (α-CD20) tumor-targeting component and an azide- and yttrium-90-(90Y) dual-functionalized dendrimer. The physicochemical properties of both pretargeting components have been extensively studied. We demonstrated that an optimized dual-functionalized dendrimer can undergo rapid strain-promoted azide-alkyne cycloaddition with the DBCO-functionalized α-CD20 at the physiological conditions. The treatment effector in our pretargeting system can not only selectively deliver radionucleotides to the target tumor cells but also increase the complement-dependent cytotoxicity of α-CD20 and thus enhance the antitumor effects, as justified by comprehensive in vitro and in vivo studies in mouse NHL xenograft and disseminated models.

A purified, fermented, extract of Triticum aestivum has lymphomacidal activity mediated via natural killer cell activation.

Non-Hodgkin lymphoma (NHL) affects over 400,000 people in the United States; its incidence increases with age. Treatment options are numerous and expanding, yet efficacy is often limited by toxicity, particularly in the elderly. Nearly 70% patients eventually die of the disease. Many patients explore less toxic alternative therapeutics proposed to boost anti-tumor immunity, despite a paucity of rigorous scientific data. Here we evaluate the lymphomacidal and immunomodulatory activities of a protein fraction isolated from fermented wheat germ. Fermented wheat germ extract was produced by fermenting wheat germ with Saccharomyces cerevisiae. A protein fraction was tested for lymphomacidal activity in vitro using NHL cell lines and in vivo using mouse xenografts. Mechanisms of action were explored in vitro by evaluating apoptosis and cell cycle and in vivo by immunophenotyping and measurement of NK cell activity. Potent lymphomacidal activity was observed in a panel of NHL cell lines and mice bearing NHL xenografts. This activity was not dependent on wheat germ agglutinin or benzoquinones. Fermented wheat germ proteins induced apoptosis in NHL cells, and augmented immune effector mechanisms, as measured by NK cell killing activity, degranulation and production of IFNγ. Fermented wheat germ extract can be easily produced and is efficacious in a human lymphoma xenograft model. The protein fraction is quantifiable and more potent, shows direct pro-apoptotic properties, and enhances immune-mediated tumor eradication. The results presented herein support the novel concept that proteins in fermented wheat germ have direct pro-apoptotic activity on lymphoma cells and augment host immune effector mechanisms.

CAT-02-106, a Site-Specifically Conjugated Anti-CD22 Antibody Bearing an MDR1-Resistant Maytansine Payload Yields Excellent Efficacy and Safety in Preclinical Models.

Hematologically derived tumors make up ∼10% of all newly diagnosed cancer cases in the United States. Of these, the non-Hodgkin lymphoma (NHL) designation describes a diverse group of cancers that collectively rank among the top 10 most commonly diagnosed cancers worldwide. Although long-term survival trends are improving, there remains a significant unmet clinical need for treatments to help patients with relapsed or refractory disease, one cause of which is drug efflux through upregulation of xenobiotic pumps, such as MDR1. CD22 is a clinically validated target for the treatment of NHL, but no anti-CD22 agents have yet been approved for this indication. Recent approval of an anti-CD22 antibody-drug conjugate (ADC) for the treatment of relapsed/refractory ALL supports the rationale for targeting this protein. An opportunity exists for a next-generation anti-CD22 antibody-drug conjugate (ADC) to address unmet medical needs in the relapsed/refractory NHL population. We describe a site-specifically conjugated antibody-drug conjugate, made using aldehyde tag technology, targeted against CD22 and bearing a noncleavable maytansine payload that is resistant to MDR1-mediated efflux. The construct was efficacious against CD22+ NHL xenografts and could be repeatedly dosed in cynomolgus monkeys at 60 mg/kg with no observed significantly adverse effects. Exposure to total ADC at these doses (as assessed by AUC0-inf) indicated that the exposure needed to achieve efficacy was below tolerable limits. Together, the data suggest that this drug has the potential to be used effectively in patients with CD22+ tumors that have developed MDR1-related resistance to prior therapies. Mol Cancer Ther; 17(1); 161-8. ©2017 AACR.

Targeting CD74 with Novel Antibody Drug Conjugates (ADCs) for the Treatment of B-Cell Non-Hodgkin's Lymphoma (NHL)

CD74 is a type II transmembrane glycoprotein involved in the formation and transport of MHC class II protein. High expression of CD74 has been confirmed in follicular lymphoma, diffuse large B-cell lymphoma (DLBCL), chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) and other types of NHL with immunohistochemistry (IHC) using the LL1 antibody (Stein et al. Clin Cancer Res 2007). We employed site-specific conjugation technology to generate novel CD74-targeting ADCs, SP7676 and SP7675 (STRO-001) that exhibit a high degree of homogeneity characterized by the drug linker covalently binding to a single defined site. The human anti-CD74 IgG1 antibody (SP7219) used for ADCs SP7676 and STRO-001 was engineered using novel Fab-based ribosome display methods enabling selection from ~1012 different antibody variants. Hundreds of unique Fabs from this selection were converted to IgGs and expressed directly in Sutro's proprietary cell-free protein synthesis platform, Xpress CFTM, for extensive screening. The top antibody lead derived from this screen is further tested to identify the best sites for conjugation of linker-warheads. Sutro's SP7219 emerged as the top performing antibody and was conjugated to noncleavable DBCO-maytansinoid linker-warheads to form the ADCs SP7676 and STRO-001. Since conjugation sites were selected based on highest stability both in vitro and in vivo, these novel ADCs lose little drug moiety in circulation and have potential for improved PK, safety and activity profiles. In vitro cell proliferation/cytotoxicity assays show potent activity in 1) DLBCL (germinal center B-cell-like [GCB] and "double-hit") lines: SU-DHL-4, IC50 - 1nM; SU-DHL-6, IC50 - 0.4 nM; WSU-NHL, IC50 - 1.6 nM; Pfeiffer, IC50 - .09 nM; NUDUL-1, IC50 - 0.4 nM; HT, IC50 - 0.7 nM; OCI-LY-19, IC50 - 0.7 nM; WSU-DLBCL2, IC50 - 0.3 nM; 2) mantle cell lymphoma (MCL) cell lines: Mino, IC50 - 0.4-0.7 nM; JVM-2, IC50 - 1.7-2.9 nM; Jeko-1, IC50 - 0.4 - 0.6 nM; 3) Ph+ acute lymphoblastic leukemia (ALL): SUP-B15, IC50 - 3.9-4.6 nM; and 4) CLL (EBV-transformed): JVM-13, IC50 - 3.0-3.4 nM. SP7676 elicited strong anti-tumor response in the OCI-LY-10 lymphoma xenograft model with 100% of animals achieving complete regression of tumors at 3mg/kg every 3 days x 5 doses and 10 mg/kg weekly x 3 doses. In the WSU-DLCL2 "double-hit" lymphoma xenograft model, administration of SP7676 (with re-dosing at time of re-growth) produced tumor regressions at 10 mg/kg every 3 days x 5 (6/8 mice tumor free, remaining 2 with small tumors) and 10 mg/kg weekly x 3 (tumor regression in most animals, 4/8 tumor free). Additionally, STRO-001 exhibits dose-dependent tumor growth inhibition in SUDHL-6 xenografts starting at 2.5 mg/kg weekly x 3 doses. Exploratory testing of our lead candidate, STRO-001 in cynomologous monkeys showed dose-dependent B-cell depletion at 1 - 30 mg/kg doses on Day 1 and 15, confirming the intended pharmacodynamic effect. Our preliminary data demonstrate that SP7676 and STRO-001 generate potent cell killing activity across multiple B-cell lymphoma/leukemia cell lines in vitro, and anti-tumor activity in preclinical B-cell NHL xenografts. Evaluation of STRO-001 in other cell lines and xenograft models and in combination studies is ongoing. GLP toxicology and other IND-enabling studies are planned. DisclosuresLi:Sutro Biopharma: Employment. Abrahams:Sutro Biopharma: Employment. Embry:Sutro Biopharma: Employment. Yu:Sutro Biopharma: Employment. Kahana:Celgene: Employment. Brown:Celgene: Employment. Narla:Celgene: Employment. Barnes:Celgene: Employment. Schwartz:Celgene: Employment. Boylan:Celgene: Employment. Zawada:Sutro Biopharma: Employment. Stephenson:Sutro Biopharma: Employment. Bruhns:Sutro Biopharma: Employment. Bussell:Sutro Biopharma: Employment. Steiner:Sutro Biopharma: Employment. Galan:Sutro Biopharma: Employment. Kline:Sutro Biopharma: Employment. Yam:Sutro Biopharma: Employment. Stafford:Sutro Biopharma: Employment. Hoffmann:Sutro Biopharma: Employment. Matheny:Sutro Biopharma: Employment. DeAlmeida:Sutro Biopharma: Employment. Vasquez:Sutro Biopharma: Employment. Heinsohn:Sutro Biopharma: Employment. Sato:Sutro Biopharma: Employment. Molina:Sutro Biopharma: Employment. Hallam:Sutro Biopharma: Employment. Lupher:Sutro Biopharma: Employment.

Results of a Phase Ib Study of Venetoclax Plus R- or G-CHOP in Patients with B-Cell Non-Hodgkin Lymphoma

Results of a Phase Ib Study of Venetoclax Plus R- or G-CHOP in Patients with B-Cell Non-Hodgkin Lymphoma

Anti-tumor activity of selective inhibitor of nuclear export (SINE) compounds, is enhanced in non-Hodgkin lymphoma through combination with mTOR inhibitor and dexamethasone

In previous studies we demonstrated that targeting the nuclear exporter protein exportin-1 (CRM1/XPO1) by a selective inhibitor of nuclear export (SINE) compound is a viable therapeutic strategy against Non-Hodgkin Lymphoma (NHL). Our studies along with pre-clinical work from others led to the evaluation of the lead SINE compound, selinexor, in a phase 1 trial in patients with CLL or NHL (NCT02303392). Continuing our previous work, we studied combinations of selinexor-dexamethasone (DEX) and selinexor-everolimus (EVER) in NHL. Combination of selinexor with DEX or EVER resulted in enhanced cytotoxicity in WSU-DLCL2 and WSU-FSCCL cells which was consistent with enhanced apoptosis. Molecular analysis showed enhancement in the activation of apoptotic signaling and down-regulation of XPO1. This enhancement is consistent with the mechanism of action of these drugs in that both selinexor and DEX antagonize NF-κB (p65) and mTOR (EVER target) is an XPO1 cargo protein. SINE compounds, KPT-251 and KPT-276, showed activities similar to CHOP (cyclophosphamide–hydroxydaunorubicin–oncovin–prednisone) regimen in subcutaneous and disseminated NHL xenograft models in vivo. In both animal models the anti-lymphoma activity of selinexor is enhanced through combination with DEX or EVER. The in vivo activity of selinexor and related SINE compounds relative to ‘standard of care’ treatment is consistent with the objective responses observed in Phase I NHL patients treated with selinexor. Our pre-clinical data provide a rational basis for testing these combinations in Phase II NHL trials.

The HB22.7-vcMMAE antibody-drug conjugate has efficacy against non-Hodgkin lymphoma mouse xenografts with minimal systemic toxicity.

In this study, HB22.7, an anti-CD22 monoclonal antibody, was used for specific, targeted delivery of monomethyl auristatin E (MMAE) to non-Hodgkin lymphoma (NHL). MMAE was covalently coupled to HB22.7 through a valine-citrulline peptide linker (vc). Maleimide-functionalized vcMMAE (mal-vcMMAE) was reacted with thiols of the partially reduced mAb. Approximately 4 molecules of MMAE were conjugated to HB22.7 as determined by residual thiol measurement and hydrophobic interaction chromatography-HPLC (HIC-HPLC). HB22.7-vcMMAE antibody-drug conjugate (ADC) retained its binding to Ramos NHL cells and also exhibited potent and specific in vitro cytotoxicity on a panel of B cell NHL cell lines with IC50s of 20-284ng/ml. HB22.7-vcMMAE also showed potent efficacy in vivo against established NHL xenografts using the DoHH2 and Granta 519 cell lines. One dose of the ADC induced complete and persistent response in all DoHH2 xenografts and 90% of Granta xenografts. Minimal toxicity was observed. In summary, HB22.7-vcMMAE is an effective ADC that should be evaluated for clinical translation.